During the first half of the previous decade, workers at a highway-widening project in California's Leguna Canyon uncovered a huge batch of fossils. Because the state of California mandates the presence of a paleontologist and an archaeologist at such digs, many of these fossils were identified as unique and scurried away for further analysis. Now, nearly ten years later, two scientists who had been supervising the project announced they had discovered four new whale species.

Top illustration: Ho New/Reuters.

As reported in Science, paleontologist Meredith Rivin of the John D. Cooper Archaeological and Paleontological Center in Fullerton, California identified the new species as being early toothed baleen whales who lived about 17 to 19 million years ago. This makes them the youngest known toothed whale species ever discovered.

Carolyn Gramling writes:

Three of the fossils belong to the genus Morawanocetus, which is familiar to paleontologists studying whale fossils from Japan, but hadn't been seen before in California. These three, along with the fourth new species, which is of a different genus, represent the last known occurrence of aetiocetes, a family of mysticetes that coexisted with early baleen whales. Thus, they aren't ancestral to any of the living whales, but they could represent transitional steps on the way to the toothless mysticetes.

The fourth new species-dubbed "Willy"-has its own surprises, Rivin says. Although modern baleen whales are giants, that's a fairly recent development (in the last 10 million years). But Willy was considerably bigger than the three Morawanocetus fossils. Its teeth were also surprisingly worn — and based on the pattern of wear as well as the other fossils found in the Laguna Canyon deposit, Rivin says, that may be because Willy's favorite diet may have been sharks. Modern offshore killer whales, who also enjoy a meal of sharks, tend to have similar patterns of wear in their teeth due to the sharks' rough skin.